Linear distance measurement by non-driven arm

Abstract

The linear distance measurement apparatus comprises a non-driven arm that is mounted such that an arc movement of the arm describes a linear distance. A rotary sensor mechanism is coupled to the non-driven arm. The sensor measures the arc movement of the arm and translates the arc movement to the linear distance.

1. A linear distance measurement apparatus comprising:
 a moveable arm mounted such that an arc movement of the arm describes a linear distance wherein the arm is not directly driven and the arm is adapted to telescope as it moves through the arc such that a first end of the arm moves only substantially linearly along the linear distance; and 
 a rotary sensor mechanism, coupled to a remaining end of the movable arm, for sensing the arc movement of the arm and translating the arc movement to the linear distance. 
 
   
   
     2. The apparatus of  claim 1  wherein the sensor mechanism is an optical encoder. 
   
   
     3. The apparatus of  claim 1  wherein the sensor mechanism electrically detects rotation. 
   
   
     4. The apparatus of  claim 3  wherein the sensor mechanism is one of a potentiometer or a magnetic sensor. 
   
   
     5. The apparatus of  claim 1  wherein the first end of the movable arm that is opposite the rotary sensor mechanism is mounted to a slide gate. 
   
   
     6. A linear distance measurement apparatus comprising:
 a movable, extendable arm having a plurality of extension sections adapted to telescope within a main section wherein the arm is not directly driven and the arm is adapted to telescope both in and out as it moves through an arc such that a first end of the arm moves only in a linear fashion; and 
 a rotary sensor mechanism, coupled to an opposite end of the arm from the first end, for sensing the arc movement of the arm and translating the arc movement to a linear distance along which the first end moves. 
 
   
   
     7. The apparatus of  claim 6  wherein the rotary sensor mechanism is an encoder that is adapted to sense a rotary motion of the coupled end of the non-driven arm. 
   
   
     8. The apparatus of  claim 7  wherein the encoder is an optical encoder that converts light patterns to determine a degree of rotation of the non-driven arm. 
   
   
     9. The apparatus of  claim 6  and further including a sensor processor coupled to the rotary sensor mechanism to perform the translation of the arc movement to the linear distance. 
   
   
     10. A slide gate system comprising:
 a slide gate that is adapted to move; 
 means for moving the slide gate; and 
 a linear distance measurement apparatus coupled to the slide gate and not connected to 
 the means for moving, the apparatus comprising:
 a moveable arm mounted such that an arc movement of the arm describes a linear distance wherein the arm is not directly driven and the arm is adapted to telescope as it moves around the arc such that a first end of the arm moves only substantially linearly along the linear distance; and 
 a rotary sensor mechanism, coupled to a remaining end of the movable arm, for sensing the arc movement of the arm and translating the arc movement to the linear distance. 
 
 
   
   
     11. The system of  claim 10  wherein the means for moving includes an electric motor coupled to a rack and pinion system. 
   
   
     12. The system of  claim 10  wherein the means for moving includes a screw drive. 
   
   
     13. The system of  claim 10  wherein the slide gate is adapted to move laterally between an open and a closed position in a frame assembly. 
   
   
     14. A method for measuring a linear distance as indicated by a movable, extendable arm coupled to a rotary sensor mechanism in a slide gate system, the method comprising:
 detecting an arc movement of the movable, extendable arm wherein an opposite end of the arm from the sensor mechanism coupled end moves only along a substantially linear path in response to a telescoping movement of the arm; 
 determining an angle of the arm with a predetermined reference point; 
 determining a sine value of the angle; and 
 determining a linear length along the substantially linear path that corresponds to the sine value. 
 
   
   
     15. The method of  claim 14  and further including calibrating the movable, extendable arm and a sensor processor to determine the reference point. 
   
   
     16. The method of  claim 15  wherein the reference point is a closed position of the slide gate.